Accelerated wear testing shows that thermoplastic bushings could be a cost-effective and durable alternative to traditional bearings for wheelchair caster use.

Abstract

Introduction: Wheelchair caster bearings often suffer high-risk failures that lead to adverse consequences such as user injuries, suggesting that design improvements are necessary. This study aimed to compare thermoplastic bushings to standard roller bearings for potential improvements in durability and cost-effectiveness.

Methods: The durability and cost-effectiveness of two thermoplastic bushing models and two metallic ball-bearing models were tested using a standard lab-based accelerated wear testing protocol. Bushings and bearings were installed on a standard 8″ caster, and four samples per model underwent testing (16 total samples).

Results: All failures were experienced by the stem rolling element. The thermoplastic bushings experienced higher mean durability than the standard ball-bearings. There were significant differences in durability across the tested models, F(3,12) = 3.88, p = 0.04. The durability of thermoplastic bushing #2 was higher than the standard type ZZ shielded deep groove ball bearings, p < 0.05. There were significant differences in cost-effectiveness across the tested models, F(3,12) = 7.64, p = 0.004. The cost-effectiveness of both thermoplastic bushings were significantly higher compared to type 2RS sealed deep groove bearings, p < 0.05.

Conclusions: The use of thermoplastic bushings can lower product cost and potentially reduce caster failures in the community that are associated with adverse consequences including user injuries.